Everything is relative. Define safe. And define country. In some countries it is safe in a sense that you are not very likely to get raped or robbed where as in other countries it might be very risky. The thing to understand is that the apps are good for finding casual sex partners, not so good for making friends or finding serious relationships.
Depends on what you want out of the apps. Personally, I felt like I was trying to buy a car when I reluctantly tried dating apps. I started to then get annoyed with people because I felt most people were being clingy or desperate-even if they truly weren't. I guess I prefer to meet guys in person-even if it's rare.
